The present invention relates to a data recording and reproducing apparatus, and more particularly to a data recording and reproducing apparatus for improving the data recording efficiency of a recording medium.
A general magnetic disk apparatus is now described as an example of a conventional data recording and reproducing apparatus.
The magnetic disk apparatus includes a magnetic disk, a recording circuit for recording data in the magnetic disk, a reproduction circuit for reproducing data from the magnetic disk, and a control circuit for controlling the recording and reproduction operation.
FIG. 13 shows a structure of a magnetic disk.
Concentric tracks t are formed on the magnetic disk 2. Sectors c partitioned by gaps g for absorbing rotational variation or fluctuation of the magnetic disk are formed on the track t. Further, servo areas s are formed intermittently in the circumferential direction of the magnetic disk. When one sector c is divided by the servo area s, the sector c is named a split sector. The sector c which is not divided by the servo area s is named a non-split sector.
FIG. 14 is a diagram for explaining an arrangement of information on the track and an index pulse signal IDX, a servo gate signal SG and a sector pulse signal SP for controlling the recording timing and the reproduction timing.
The index pulse signal IDX is a signal indicative of a start point of the track and is generated once per rotation of the magnetic disk 2.
The servo gate signal SG is a signal indicative of the servo area and is generated at regular intervals from the index pulse signal IDX.
The sector pulse signal SP is a signal indicative of a start point of the sector and is generated on the basis of the index pulse signal IDX.
Upon Recording of Data
Recording of data is made as follows:
The control circuit activates a write gate signal WG for a sector in which data is to be recorded in response to the sector pulse signal SP. At the same time, the control circuit produces to a data bus NRZ a series of sector information, that is, a bit synchronization information PLO, a symbol synchronization information SYNC, data DATA, an error check code ECC used to perform error detection and correction, and pad information PAD for absorbing reproduction delay. When the series of sector information is produced, the control circuit activates a write gate signal WG.
The recording circuit records the series of sector information produced to the data bus NRZ on the track t of the magnetic disk 2 after the elapse of a delay named a record delay. The time corresponding to the record delay is previously contained in the series of sector information and a length of data actually recorded on the track t is shorter than a length of the series of sector information.
Upon Reproduction of Data
Reproduction of data is made as follows:
The control circuit activates a read gate signal RG for a sector from which data is to be reproduced in response to the sector pulse signal SP.
When the read gate signal RG is activated, the reproduction circuit produces the bit synchronization information PLO to reproduce the symbol synchronization information SYNC, the data DATA, the error check code ECC and the pad information PAD succeeding to the bit synchronization information PLO on the magnetic disk and produces them to the data bus NRZ.
In this connection, the symbol synchronization information SYNC, the data DATA, the error check code ECC and the pad information PAD produced to the data bus NRZ are delayed by a time required for reproduction processing as compared with the symbol synchronization information SYNC, the data DATA, the error check code ECC and the pad information PAD on the magnetic disk. This delay time is named a reproduction delay time.
The control circuit detects the beginning of the data DATA in response to detection of the symbol synchronization information SYNC on the data bus NRZ and processes the data DATA and the error check code ECC. Further, the control circuit inactivates the read gate signal RG after the time corresponding to the number of bytes of data to be transferred, starting from the detection of the symbol synchronization information SYNC.
When the read gate signal RG is inactivated, the reproduction circuit stops outputting of the data reproduced from the magnetic disk.